A Note on a Theorem in Group Theory

Prof. Chang Yuanda proved Theorem 4 in his well-knownbook "Structure of Finite Groups" (in Chinese) (P.49). and pointed out that the condition that﹝G:N_G(H)﹞ is finite was the key of the theorem. In this note, it is shown that the codition can be left out, and a more general theorem has been proved.